@theme-color: #DF0011;
.switch{
  width: 36px;
  height: 16px;
  padding: 2px;
  border-radius: 3px;
  background: #ccc;
  transition: all 300ms;
  .switch-inner{
    position: relative;
    left: 0;
    width: 12px;
    height: 12px;
    border-radius: 2px;
    background: #fff;
    transition: all 300ms;
  }
}

.switch--checked{
  background: @theme-color;
  .switch-inner{
    left: 20px;
  }
}